Method of Operating a Communication Device Operable in an Active Mode and in an Idle Mode, a Computer Program Product for Executing the Method, and the Communication Device Operable in an Active Mode and in an Idle Mode

ABSTRACT

A method of operating a communication device comprises providing the communication device (T, T 1 -T 5 ) with a first interface ( 11 ) to connect to a first network (N 1 ), which provides a first bandwidth and a first network idle power consumption at the communication device (T, T 1 -T 5 ), when being connected to the first network (N 1 ) and providing the communication device (T, T 1 -T 5 ) with a second interface (I 2 ) to connect to a second wireless network (N 2 ), which provides a second bandwidth, which is smaller than the first bandwidth, and a second network idle power consumption, which is smaller than the first idle power consumption, at the communication device (T, T 1 -T 5 ), when being connected to the second wireless network (N 2 ).

CROSS REFERENCE TO RELATED APPLICATIONS

This application is the United States national phase under 35 U.S.C.§371 of PCT International patent application no. PCT/EP2012/002410,filed on Jun. 6, 2012.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Embodiments relate to methods of operating a communication device whichis operable in an active mode and in an idle mode. The invention furtherrelates to a computer program product for executing such a method and tothe communication device which is operable in an active mode and in anidle mode.

2. Background of the Related Art

Modern communication devices such as mobile phones or IP phones (IP:Internet Protocol) are usually connected to a network such as theinternet for communication purposes. Most of the time the device may bein an idle mode and only for short periods of time the device is in anactive mode. In data communications, an idle mode may be defined as amode in which no transmissible data are present on a given connection.In particular, during the idle mode, services of the data link layer orlink layer (OSI layer 2) are not provided for data exchange. The bittransmission layer or physical layer (OSI layer 1) may be able totransfer data, but the data link layer is neither able to send nor toreceive instructions or messages. Therefore, a communication instance ofthe data link layer is unable to operate according to an appointedprotocol in the idle mode. Whereas organizational data traffic such astransmission of signaling data may occur, in the idle mode there is notraffic of payload data. An idle mode frequently occurs when at a wiredcommunication device such as an office phone, a handle of the wiredcommunication device is on-hook. In mobile communications, the idle modemay be defined as the mode in which there is no active networkconnection, a mobile communication device in the idle mode maypermanently search for a radio cell suitable to be connected to whereinorganizational channels (BCCH, CCCH, CBCH) of the radio cell arepermanently received and processed by the mobile communication device.Such data traffic which is required for maintaining the communicationdevice to be able to send and/or receive payload data is not regardedpayload data traffic but regarded to be comprised by signaling datatraffic. A mobile communication device such as a mobile phone frequentlyswitches into the idle mode when there is no active network connectionwhich is established if a user of the mobile communication deviceinitiates a phone call. An active network connection is also establishedif an answering machine of a wired or mobile communication device isoperating to send and/or receive a message. In the following, the idlemode of a communication device may be defined as the mode in which anestablished physical layer and an established data link layer of anetwork are dispensable for data transmission.

In contrast, to the idle mode, the active mode may be defined as a modeof a communication device in which an active network connection isestablished or is necessary to be established. Payload data which a userof the communication device wants to transmit to another communicationdevice of another user is transmitted over the active networkconnection. Before, during or after the payload transmission, signalingdata transmission may occur. For transmitting communication databidirectionally and in real time, such as speech data and/or video data,high bandwidth network connections are required in the active mode. Onthe other hand, in the idle mode, when no payload data is to betransferred, a power consumption of the mobile device should be as lowas possible. In the following, the active mode of a communication devicemay be defined as the mode in which an established physical layer and anestablished data link layer of a network are required for datatransmission.

IP phones are often connected via Ethernet. Ethernet is an example of alocal area network (LAN) which is a computer network that interconnectscomputers in a limited area such as a home, school, computer laboratory,or office building using network media. The defining characteristics ofLANs in contrast to wide area networks (WANs) or global area networks(GANs) include their usually higher data transfer rates, smallergeographic area, and lack of a need for leased telecommunication lines.Usually, a LAN is limited in its extension without further measures ofapproximately 500 m. The power consumption of the Ethernet itself,meaning the Ethernet connection to a communication device without thecommunication device, is approximately between 10 and 100 mW. Currentlyused IP phones are unable to decrease their power consumptionsignificantly under 1000 mW because of the used components and the usedhardware design. Therefore, the power consumption of the Ethernet itselfis negligible with respect to the power consumption of the communicationdevice connected to the Ethernet.

However, with recent power efficient components such as microcontrollers(MCUs) which are able to operate below approximately 10 mW in low powermode or approximately 100 μA in sleep mode, the power consumption of theEthernet connection is not negligible any more with respect to the powerconsumption of the communication device comprising such amicrocontroller. A microcontroller or microcontroller unit commonly is asingle chip that contains a processor, RAM, ROM (read only memory) clockand I/O (input/output) control unit. A low power mode of amicrocontroller may be established for example by switching off externalcircuits, power budgeting measures, configuring port pins, using highvalue pool-up resistors, reducing operating voltage, using an externalsource for CPU (central processing unit) core voltage, and/or using abattery backup for the microcontroller. A sleep mode of amicrocontroller also called standby mode is often established in thatthe microcontroller's high frequency clock oscillator remains running,but the clock tree that drives the CPU circuitry is disabled. In sleepmode, the high-frequency peripheral clock trees are commonly kept alive,allowing autonomous functioning of high-speed peripherals such as adirect memory access (DMA), high-speed serial ports, analog-to-digitaland digital-to-analog converters and AES (Advanced Encryption Standard)encryption/decryption. In sleep mode, the RAM (Random Access Memory)remains active and may be accessed by the DMA controller, allowing dataretrieved by peripherals to be stored without CPU intervention (CPU:Central Processing Unit). The power consumption of a microcontroller canbe lowered even more in the so called deep sleep mode, in which the highfrequency MCU oscillator is disabled but the oscillator used to drivecritical peripherals is kept running. These may include the real-timeclock (RTC) and a watchdog timer as well as a power-on reset and abrown-out detection circuitry.

Such advanced MCUs are able to provide a current draw in deep sleep modeof 0.59 μA and still retain full register and RAM contents. For otherMCUs the current consumption may range from 10 μA to 30 μA. The time toreturn to active mode will vary from 2 μs for an optimized design to 8μs. With such advanced microcontrollers being widely utilized in moderncommunication devices the power consumption of the network thecommunication device is connected to, for example the Ethernet accordingto IEEE 802.3 standard, is not negligible anymore and should be loweredas much as possible for efficient usage of energy. IEEE 802.3 is aworking group and a collection of IEEE standards by the working groupdefining the physical layer and data link layer's media access control(MAC) of wired Ethernet. Physical connections are usually made betweennodes and/or infrastructure devices such as hubs, switches, and/orrouters by various types of copper or fiber cable. In an effort toreduce the power consumption of Ethernet-LANs the IEEE 802.3az standardhas been ratified in September 2010, also called energy-efficientEthernet or Green Ethernet. This standard is a set of enhancements tothe twisted-pair and backplane Ethernet family of computer networkingstandards that will allow for less power consumption during periods oflow data activity.

BRIEF SUMMARY OF THE INVENTION

Embodiments may lower the power consumption of a communication deviceconnected to a network by the provision of a method of operating thecommunication device, a computer program product for executing themethod, and a respective communication device. The lowered powerconsumption of the communication device should be realized in a simpleway which is low-cost, leads to a low power consumption in the idlemode, sufficient bandwidth for data transmission available in the activemode, and allow for switching between the idle mode and the active modecontrollable from the network.

An inventive method of operating a communication device comprises thefollowing steps. Providing the communication device with a firstinterface to connect to a first network, which provides a firstbandwidth and a first network idle power consumption at thecommunication device, when being connected to the first network,providing the communication device with a second interface to connect toa second wireless network, which provides a second bandwidth, which issmaller than the first bandwidth, and a second network idle powerconsumption, which is smaller than the first idle power consumption, atthe communication device, when being connected to the second wirelessnetwork, when in an active mode of the communication device anestablished physical layer and an established data link layer of thefirst network are required for data transmission, establishing by acontroller unit a first communication link between the communicationdevice and the first network over the first interface, and, when in anidle mode of the communication device the established physical layer andthe established data link layer of the first network are dispensable fordata transmission, disconnecting, by the controller unit the firstcommunication link and establishing a second communication link betweenthe communication device and the second wireless network over the secondinterface. The first network may be a local area network such as IEEE802.3 Ethernet or a global area network such as GSM (Global Standard forMobile communication). The second wireless network may be an IEEE802.15.4 low rate wireless personal area network. The IEEE 802.15.4standard specifies the physical layer and media access control for LowRate Wireless Personal Area Networks (LR-WPANs). The reach of such aWireless Personal Area Network (WPAN) varies from a few centimeters to afew meters. A Personal Area Network (PAN) may also be carried over wiredcomputer buses such as USB (Universal Serial Bus) and FireWire. Thesecond wireless network may also be and/or comprise ZigBee, ISA100.11a,WirelessHART, and/or MiWi specifications, each of which definingnetworks extending the standard of IEEE 802.15.4 by developing the upperlayers which are not defined by this standard. The second wirelessnetwork may also be built as a Wireless Embedded Internet by using6L0WPAN and standard Internet protocols.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 a schematic diagram of a communication system according to theinvention,

FIGS. 2A to 2G schematic diagrams of communication devices according tothe invention connected to the first network and the second wirelessnetwork in different embodiments,

FIG. 3 the inventive communication system wherein the first network isan Ethernet and the second network is a low rate wireless personal areanetwork, and

FIG. 4 a flowchart for switching between the idle mode and the activemode according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

As previously noted, embodiments may lower the power consumption of acommunication device connected to a network by the provision of a methodof operating the communication device, a computer program product forexecuting the method, and a respective communication device. The loweredpower consumption of the communication device should be realized in asimple way which is low-cost, leads to a low power consumption in theidle mode, sufficient bandwidth for data transmission available in theactive mode, and allow for switching between the idle mode and theactive mode controllable from the network.

An inventive method of operating a communication device comprises thefollowing steps. Providing the communication device with a firstinterface to connect to a first network, which provides a firstbandwidth and a first network idle power consumption at thecommunication device, when being connected to the first network,providing the communication device with a second interface to connect toa second wireless network, which provides a second bandwidth, which issmaller than the first bandwidth, and a second network idle powerconsumption, which is smaller than the first idle power consumption, atthe communication device, when being connected to the second wirelessnetwork, when in an active mode of the communication device anestablished physical layer and an established data link layer of thefirst network are required for data transmission, establishing by acontroller unit a first communication link between the communicationdevice and the first network over the first interface, and, when in anidle mode of the communication device the established physical layer andthe established data link layer of the first network are dispensable fordata transmission, disconnecting by the controller unit the firstcommunication link and establishing a second communication link betweenthe communication device and the second wireless network over the secondinterface. The first network may be a local area network such as IEEE802.3 Ethernet or a global area network such as GSM (Global Standard forMobile communication). The second wireless network may be an IEEE802.15.4 low rate wireless personal area network. The IEEE 802.15.4standard specifies the physical layer and media access control for LowRate Wireless Personal Area Networks (LR-WPANs). The reach of such aWireless Personal Area Network (WPAN) varies from a few centimeters to afew meters. A Personal Area Network (PAN) may also be carried over wiredcomputer buses such as USB (Universal Serial Bus) and FireWire. Thesecond wireless network may also be and/or comprise ZigBee, ISA100.11a,WirelessHART, and/or MiWi specifications, each of which definingnetworks extending the standard of IEEE 802.15.4 by developing the upperlayers which are not defined by this standard. The second wirelessnetwork may also be built as a Wireless Embedded Internet by using6L0WPAN and standard internet protocols.

The controller unit may be a microcontroller unit or microcontroller ora central processing unit. Not integrated, discrete or partiallydiscrete solutions of a controller may be used as a controller unit aswell. The first network may be a wireless or wired network. For example,the first network may be a wireless GSM-network or a wired Ethernet-LAN.With the power consumption of the communication device in the idle modecomprising the power consumption of the communication device and thepower consumption of the network at the interface the communicationdevice is connected to the network, the power consumption of thecommunication device in the idle mode depends on the kind of network thecommunication device is connected to. Since the power consumption of thecommunication device in idle mode is lower with the communication devicebeing connected to the second wireless network then being connected tothe first network, the communication device when being operated in theidle mode is advantageously disconnected flora, the first network andconnected to the second wireless network by establishing a secondcommunication link between the communication device and the secondwireless network of the second interface. On the other hand, with alarger power consumption of a network usually being associated with alarger possible bandwidth, when the communication device is operated inthe active mode, a first communication link is established between thecommunication device and the first network over the first interface fortransmission of payload data. The inventive method thus combines theadvantages of two networks by utilizing a first network with a largerpower consumption for transmission of data at sufficient bandwidth, e.g.payload data, while utilizing a second wireless network with a lowerpower consumption in the idle mode when the higher bandwidth of thefirst network is not required, e.g. only signaling data is to betransmitted. For transmitting signaling data, the bandwidth of thesecond network may be sufficient whereas for transmission of payloaddata it is not. This way in the communication device a transceiver of afirst wired or wireless network may be advantageously combined with asecond transceiver of a second wireless network to operate in the idlemode with a lower power consumption and to operate in the active modewith a larger bandwidth which may be required for transmission of data,e.g. real time and/or bidirectional data such as speech and/or videodata. Thus, the active mode may be required if a higher bandwidth and/ora lower latency are/is needed for (uninterrupted) data transmission thanthe wireless second network connection could offer. The bandwidthrequirement and/or latency requirement are/is dependent upon the qualityof service associated with the data to be transmitted. For example,video data usually has higher requirements in bandwidth and/or latencythan speech data, whereas speech data usually has higher requirements inbandwidth and/or latency than transmitting data files such as textand/or picture data. Additionally, the bandwidth requirement and/orlatency requirement are/is dependent on the codec used. By combining theadvantage of the first network of a larger bandwidth and the lower powerconsumption in the idle mode of the second wireless network andeliminating the disadvantage of a larger power consumption in the idlemode of the first network and the lower bandwidth of the second wirelessnetwork the advantages of both networks are combined, the disadvantagesof both networks are eliminated and redundancy emerges by using bothnetworks in the communication device.

When the communication device is operated in the active mode, thecommunication device may be operated to route information from the firstnetwork over the second interface to another communication device whichhas been disconnected from the first network and which is connected tothe second wireless network. This way, the communication device which isconnected to the first network over the first interface acts as a routerfor another communication device which is not connected to the firstnetwork directly but indirectly by using the communication device as arouter connecting the first network with the second wireless network.When acting as a router, the respective communication device connectedto the first network over the first interface may be operated in theactive mode in order to be able to use the physical and data link layersof the first network for data transmission. Several other communicationdevices may be connected in the idle mode with the first network via thecommunication device routing information from the first network over thefirst interface and over the second interface and the second network tothe other communication devices.

When the communication device is operated in the active mode, withadvantage a communication device is operated to discover anothercommunication device which has been disconnected from the first networkand is connected to the second network and to inform the first networkor any device comprised by the network about the other communicationdevice over the first interface. This way, the reach of the firstnetwork is extended to other communication devices being in the idlemode and thus not connected to the first network over their firstinterfaces but being connected to and/or comprised by the second networkover their second interfaces only. Since transmission of signaling andpayload data is possible in the idle mode over the second network, theother communication devices which are connected to the second networkare able to send and receive information to at least one communicationdevice acting as a router for routing information from the first networkto the second network,

When the communication device is operated in the idle mode, in oneembodiment the communication device is operated to exchange a keep-alivemessage with and to receive a power control instruction from anothercommunication device connected to the second wireless network. Theexchange of a keep-alive message with another communication deviceconnected to the second wireless network while being in the idle modeallows for discovering this communication device by other communicationdevices connected to the second wireless network and routing thediscovery of this communication device in form of a message to othercommunication devices connected to the first network in the ease whereat least one communication device acts as a router between the firstnetwork and the second network. The ability to receive a power controlinstruction from another communication device enables the communicationdevice in the idle mode, when being connected to the second wirelessnetwork over the second interface and disconnected from the firstnetwork over the first interface, to be woken up by a respective powercontrol instruction transmitted from another communication device actingas a router between the first network and the second wireless networkresulting in a switch of the communication device from the idle mode tothe active mode.

When the communication device is operated in the idle mode thecommunication device may be switched to the active mode if thecommunication device is requested to by a routed instruction receivedover the second interface. In this embodiment the switching to theactive mode may be requested by a server of the first network or byalgorithms for power management distributed over the first network. Thisway, the full functionality of the communication device in the idle modeis maintained while the communication device is not connected to thefirst network over its first interface. Instead, the communicationdevice is switched to the active mode by a request of a server of thefirst network or by algorithms for power management distributed over thefirst network by reception of a routed instruction over the secondinterface of the communication device.

For maintaining a full functionality of the communication device, thecommunication device may be switched to the active mode, when thecommunication device is operated in the idle mode, if the communicationdevice is disconnected from the second wireless network over the secondinterface. Consequently, the communication device is connected to thefirst network over the first interface in the case of a disconnection ofthe communication device from the second wireless network over thesecond interface. Another case where the communication device isswitched to the active mode, when being operated in the idle mode,occurs if a power supply of the communication device indicates adysfunction. For example, the power supply of the communication devicemay comprise a rechargeable battery and the rechargeable battery is onlycharged when the communication device is operated in the active mode,thus being connected to the first network over the first interface. Thecharging power may originate from Power over Ethernet (PoE) of a wiredEthernet LAN as the first network. If the rechargeable battery of thecommunication device is no longer able to provide a sufficient powersupply for the communication device to maintain its idle mode, forexample due to loss of charge, the communication device is switched fromits idle mode to the active mode for the rechargeable battery to becharged as long as the rechargeable battery allows for the switch fromthe idle mode to the active mode. Thus, the communication device may beoperated in the active mode if a MCU of the communication device is busyand/or peripherals of the communication device need/needs power which isnot available from the rechargeable battery or capacitor of thecommunication device. The communication device is also operated inactive mode if the power level of the rechargeable battery or capacitoris lower than a predetermined threshold value, too low to maintain theidle mode, or if the rechargeable battery or capacitor is charged. Theswitching from the idle mode to the active mode may be initiated by thecommunication device in the idle mode itself or by an instruction ofanother communication device connected over its first interface to thefirst network and/or over its second interface to the second network.

When the communication device is operated in the active mode, thecommunication device may be switched to the idle mode if therechargeable battery is fully charged. This measure is particularlyuseful when the communication device is not operated by a user and theidle mode should be maintained as long as possible with the advantage oflow power consumption when the communication device is connected to thesecond wireless network over the second interface. Here, therechargeable battery should be fully charged before switching from theactive mode to the idle mode, in order to keep the communication deviceconnected to the second wireless network for a longest possible periodof time. The charging of the rechargeable battery in the active mode,when the communication device is connected to the first network over thefirst interface may be done by using a power source independent from thefirst network and from the second wireless network or by using Powerover Ethernet when a wired Ethernet LAN is used as the first network.

For being able to take advantage of the physical and data link layers offirst network for transmitting data, the communication device may beoperated to switch from the idle mode to the active mode by a user inputof a user of the communication device. The user input may be in the formof taking a handle of the communication device off-hook or by pushingany button located on the communication device or a remote device suchas a computer connected to the communication device, e.g. over aCTI-interface. The button may be in the form of a mechanical button, atouchless-button, a touchpad, a keypad or the like.

To maintain the full functionality of the communication device, it isuseful, when the communication device is operated in the idle mode tooperate the communication device to transmit a message to anothercommunication device connected to the second wireless network if thecommunication device cannot be connected to the first network over itsfirst interface and/or the communication device cannot be charged. Thisway, when the communication device cannot be connected to the firstnetwork over its first interface, at least other communication devicesbeing connected to the second network can be reached by transmitting amessage from the communication device to these other communicationdevices. Therefore, at least communication devices being connected tothe second wireless network are reachable by the communication device inthe idle mode, which may particularly be helpful in the case ofemergency. To avoid a breakdown of the communication device caused bypower failure, a single or other communication devices being connectedto the second wireless network may be reached by the communicationdevice over its second interface by transmitting a message to the singleor these other devices when the communication device cannot be charged.

A computer program product may be provided for executing the inventivemethod as outlined above. The computer program product may be a softwareproduct comprising instructions. The computer program product may becomprised by a machine-readable medium, wherein the machine-readablemedium may be a floppy disc, a CD (Compact Disc), a DVD (DigitalVersatile Disc), or any other suitable digital or analog medium.

The invention further comprises a communication device comprising: Afirst interface for connecting the communication device to a firstnetwork, which provides a first bandwidth and a first network idle powerconsumption at the communication device, when being connected to thefirst network, a second interface for connecting the communicationdevice to a second wireless network, which provides a second bandwidth,which is smaller than the first bandwidth, and a second network idlepower consumption, which is smaller than the first idle powerconsumption, at the communication device at the communication device,when being connected to the second wireless network, and a controllerunit configured to control the first interface and the second interfacesuch that, when in an active mode of the communication device anestablished physical layer and an established data link layer of thefirst network are required for data transmission, establishing a firstcommunication link between the communication device and the firstnetwork over the first interface, and, when in an idle mode of thecommunication device the established physical layer and the establisheddata link layer of the first network are dispensable for datatransmission, disconnecting the first communication link andestablishing a second communication link between the communicationdevice and the second wireless network over the second interface. Theobject of the invention is solved by this communication device for thesame reasons as outlined above with respect to the inventive method. Thecommunication device may be a mobile phone, a wired phone such as anoffice phone, a PDA (Personal Digital Assistant, a PC (personalcomputer) or tablet PC, or any other communication device comprising theapparatus features as outlined above.

The invention further comprises a communication system comprising thecommunication device as outlined above, the first network and the secondwireless network. The first network and the second wireless network maybe networks as described in connection with the inventive method. Forexample, the first network may be a global area network such as GSM or alocal area network such as an Ethernet. The second wireless network maybe an a wireless LAN or an IEEE 802.15.4 low rate wireless personal areanetwork.

Further embodiments and advantages of the invention are highlighted inthe following with respect to figures. For an improved clearness, thefigures are not true to scale or proportionate. In the figures, as longas not mentioned otherwise, same references indicate same parts withsame meaning.

In FIG. 1, an inventive communication device, is represented by acommunication terminal T. The communication terminal may be a mobilephone, IP phone, or a wired phone such as an office phone. Thecommunication terminal T comprises an interface I1, wherein a firstnetwork N1 is connected to the interface I1 over a first connection linkIA. The first network N1 is further connected to another interface IA ofa server S over another communication link IB. The first network N1 maybe a local area network such as the Ethernet or a global area networksuch as GSM. The communication terminal further comprises a thirdinterface I3, wherein the communication terminal T is connected to theserver S over connection links 3A, 3B via a network N3. The network N3may be a Public Switched Telephone Network (PSTN) complementing thenetwork N1 for a redundant connection between the communication terminalT and the server S. The communication terminal T further comprises asecond interface I2, wherein the communication terminal T is connectedover the second interface I2 to a second wireless network N2 over asecond communication link 2. The second wireless network may be awireless personal area network, for example the IEEE 802.15.4 low ratewireless personal area network. When connected to the first network fordata transmission over the first interface the communication device whenbeing operated in the idle mode has a first power consumption which islarger than the second power consumption which the communication deviceT has when being connected to the second wireless network N2 for datatransmission over the second interface I2. A first bandwidth of thefirst network is larger than a second bandwidth of the second networkusable by the communication device T when being connected to the firstand second networks, respectively. Therefore, the first network may beGSM-network while the second wireless network may be a wireless LAN.Alternatively, the first network may be a wireless or wired LAN whilethe second wireless network may be a wireless personal area network.

The interfaces I1, I2, I3 are connected to a controller unit C overconnection links 11, 12, 13. The controller unit may be amicrocontroller or a central processing unit. A keypad KP is connectedto the controller unit C over a connection link 15 and a handle H of thecommunication terminal T is connected to the controller unit C overconnection link 14. If a button of the keypad KP is pushed or the handleis taken off-hook, the communication terminal T switches from an idlemode, in which a physical layer and a data link layer of the firstnetwork N1 are dispensable or not required for data transmission, to anactive mode, in which the physical layer and the data link layer of thefirst network N1 are required or necessary for data transmission of apredetermined quality of service. The data transmission may be accordingto data to be transmitted from the user of the communication terminal Tto another communication device such as the server S or vice versa. Whenthe communication terminal is operated to switch to the active mode, thecontroller unit C establishes the first communication link 1A betweenthe communication terminal T and the first network N1 over the firstinterface I1 for the transmission of payload data. If the user is notusing the communication terminal, for example by putting the handle Hon-hook or by not pushing a button of the keypad KP for a determinedperiod of time, the communication terminal T is operated to switch tothe idle mode. In this case, the controller unit C disconnects the firstcommunication link 1A and establishes the second communication link 2between the communication terminal T and the second wireless network N2over the second interface I2. In the idle mode, a possibly presentcommunication link 3A between the interface I3 and the network N3 isdisconnected by the controller unit C as well. In the idle mode, thecommunication terminal is thus connected only to the second wirelessnetwork N2 over the second communication link 2 and the interface I2.

The controller unit C is further connected to a rechargeable battery Bover a connection link 16. The rechargeable battery which may be in theform of capacitor is only charged if the communication terminal T isconnected to the first network N1 over the interface I1 and the firstconnection link 1A. If the first network is a wired local area network,the power supply may be established by Power over Ethernet. This way,the electrical current necessary for the operation of the communicationterminal T is carried by the data cables of the LAN rather than byseparate power cords. Alternatively, the rechargeable battery B may becharged by a power source independent of the first network N1 which maybe the GSM. If the rechargeable battery is fully charged, thecommunication terminal T is switched from the active mode to the idlemode, thus being disconnected from the first network over the firstinterface I1 and being connected to the second wireless network over thesecond interface I2. If the communication terminal is in the idle mode,thus being only connected to the second wireless network, thecommunication terminal T is switched to the active mode if therechargeable battery is no longer able to supply the communicationterminal T with energy sufficient to maintain the idle mode. In thiscase, the rechargeable battery B as the power source of thecommunication terminal T indicates a dysfunction to the controller unitC. The active mode and the idle mode of the communication terminal T maybe displayed to a user of the communication terminal T by a display (notshown).

A microcontroller MC for controlling functions of the communicationterminal T is present and connected to the keypad KP, the handle H, andthe rechargeable battery B over connection links 17, 18, 19. Themicrocontroller MC is further connected to the controller unit C over aconnection link 20. The controller unit C for establishing the firstcommunication link 1A and the second communication link 2 dependent uponthe active mode and the idle node may thus be supervised by themicrocontroller MC. Alternatively, the microcontroller MC and thecontroller C are not separate entities but integrated either into themicrocontroller MC or into the controller unit C. A separate controllingunit C in addition to the present microcontroller MC is useful if thecommunication terminal T is upgraded to be able to perform the inventivemethod. When being operated in the active mode, the terminal T may beinstructed by the server S over the communication link IB, the firstnetwork N1, the first communication link 1A and the interface I1 to beswitched from the active mode to the idle mode. If in the active modethe communication terminal T is not only connected to the first networkN1 over the first interface I1 but also connected to the third networkN3 over the third interface I3, the server S may transmit an instructionto switch the communication terminal T from the active mode to the idlemode over the communication link 3B, network N3, communication link 3A,and interface I3 as well.

In FIG. 2A, several communication devices in form of communicationterminals T1, T2, T3, T4, T5 are connected to a first network N1 overcommunication links 21, 22, 23, 24, 25.

Simultaneously, the communication terminals T1-T5 are interconnected ina point-to-point, also called peer-to-peer, second wireless network N2.The communication links 31-37 of the second wireless network N2 areshown in FIG. 2A, as also is the case in FIGS. 2B-2F, as dashed lines inorder to distinguish the communication links 31-37 of the secondwireless network N2 from the communication links 21-25 of the firstnetwork N1 (straight lines). The communication system of FIG. 2Arepresents several communication devices T1-T5 in a busy time, where allthe communication devices in form of communication terminals T1-T5 arein use and in the active mode by being connected to the first network N1over their first interfaces I1. If the first network is an Ethernet LAN,as depicted in FIG. 2A, the Ethernet connections of all communicationterminals T1-T5 are established through which the communicationterminals T1-T5 are powered via Power over Ethernet resulting incharging the rechargeable battery B comprised by each of thecommunication terminals T1-T5. In the active mode, the microcontrollerunit MC comprised by each of the communication terminals T1-T5, can workwith full frequency if required to execute the functions as accessed byeach of the users of the communication terminals T1-T5. In the activemode, the communication links 21-25 are maintained not only if the firstnetwork N1 is in an active state, but also if the first network N1 is ina low power state. This situation may occur if during a phone call noneof the participants of the phone call talks while the connection betweenthe participants is established. The communication terminals T1-T5 arein the active mode and therefore connected to the first network N1 overtheir first interfaces I1 while being also connected to the secondwireless network N2 over their second interfaces I2 which is constitutedby the communication links 31-37 connecting the communication terminalsT1-T5.

In FIG. 2B, instead of a peer-to-peer or point-to-point second wirelessnetwork N2, the communication terminals T1-T5 are interconnected bycommunication links 31, 32, 34, 35 in a star pattern or starconfiguration. With respect to the second wireless network N2, thecommunication terminals T1, T3, T4, and T5 constitute endpoints of thesecond wireless network N2. The communication terminals T1, T3, T4, andT5 are in idle mode wherein these communication terminals are notconnected to the first network N1 over their respective first interfacesI1 (not shown in FIG. 2). The communication terminal T2 is in activemode and linked to the first network N1 over communication link 22. Inthe case, where the first network is an Ethernet LAN and the secondwireless network is a low rate wireless personal area network, in thecommunication terminals T1, T3, T4, and T5 the Ethernet physical layeris switched off, leading to a disconnection of these communicationterminals from the first network over their first interfaces. Incommunication terminals T1, T3, T4, T5 a rechargeable battery B or acapacitor is used in each of these terminals for power supply since noother power source is available neither by Power over Ethernet nor inform of another power source being independent from the first networkN1. A microcontroller unit (MCU) which may be present in each of thecommunication terminals T1, T3, T4, and T5 may be operated in power savemode. With the bandwidth of the second wireless network being smallerthan the bandwidth of the first network, each of the communicationterminals T1, T3, T4, and T5 sends keep-alive messages over radiofrequency to indicate to other communication devices that thecommunication terminals T1, T3, T4, and T5 may be switched from the idlemode to the active mode. The power consumption of the communicationterminals T1, T3, T4, and T5 is approximately 1-10 μW. In contrast tothe communication terminals T1, T3, T4, and T5, the communicationterminal T2 is in active mode and able to route information from thefirst network N1 over the communication link 22, its first interface I1,and its second interface I2 to the other communication terminals T1, T3,T4, and T5 thus linking the communication terminals T1, T3, T4, and T5to the first network although these communication terminals have beendisconnected from the first network over their respective firstinterfaces. By using the communication terminal 12 as a router betweenthe first network and the second wireless network N2, a server S of thefirst network N1 may transmit a power control instruction over thecommunication terminal T2 to each of the communication terminals T1, T3,T4, and T5 to be woken up from the idle mode into the active mode. Thisway, the reach of the first network N1 is extended to communicationterminals T1, T3, T4, and T5 by using the communication terminal T2 as arouter.

Another configuration of a communication system according to theinvention is illustrated in FIG. 2C. The star pattern or starconfiguration of the communication terminals T1-T5 is the same asillustrated in FIG. 2B. However, instead of the communication terminalT2 being connected to the first network N1 over communication link 22,in FIG. 2C the communication terminal T3 is in active mode and connectedto the first network N1 via communication link 23. With thecommunication terminal T3 acting as a router between the first networkN1 and the second wireless network N2 routed information, also calledrout information, from the first network N1 may be transmitted overcommunication link 23, the first interface I1 of the communicationterminal T3, second interface I2 of this terminal and over communicationlink 32 to communication terminal T2. Communication terminal T2 isacting as a coordinator of the second wireless network N2 bydistributing the route information of the first network N1 to thecommunication terminal T1 over communication link 31, to thecommunication terminal T4 over communication link 34, and tocommunication terminal T5 over communication link 35. Althoughcommunication terminal T3 is an endpoint with respect to the secondwireless network and is an endpoint with respect to the first network,this terminal is important to connect the communication terminals T1,T2, T4, and T5 of the second wireless network to the first wirelessnetwork N1. The communication terminal T2 is important for connectingthe communication terminals T1, T4, and T5, each of which is operated inthe idle mode, to the first network N1 over communication terminal T3.

A higher degree of redundancy is reached with respect to the secondwireless network N2 by a peer-to-peer or point-to-point network asillustrated in FIG. 2D. If communication link 34 between communicationterminal T2 and communication terminal T4 fails, route information fromthe communication terminal T2 is still transmitted to communicationterminal T4 over communication link 31, communication terminal T1, andcommunication link 36. However, there is no redundancy with respect tothe first network N1 since only a single communication terminal T2 isconnected to the first network N1 over communication link 22 to routeinformation from the first network N1 to communication terminals T1, T3,T4, and T5 of the second wireless network N2.

A higher degree of redundancy with respect to the first network N1 isreached by the communication system as illustrated in FIG. 2E. Insteadof only one communication terminal, T2 in FIG. 2D, being connected tothe first network N1, the communication terminal T1 is connected to thefirst network over communication link 21 and the communication terminalT3 is connected to the first network N1 over communication link 21. Bothcommunication terminals T1, T3 act as separate routers for routinginformation from the first network N1 to the second wireless network N2.Thus, communication terminal T4 may receive routing information from thefirst network N1 either over communication terminal T1 or overcommunication terminal T3. Compared to the configurations of thecommunication systems as depicted in FIG. 2B and FIG. 2C, there is atrade-off between the required redundancy with respect to the firstnetwork N1 and the second wireless network N2 and the requiredmaintenance effort for maintaining the communication links necessary tobe established to provide the required degree of redundancy. The totalpower consumption of the first network N1 and the second wirelessnetwork N2 hereby increases with an increase of the number ofcommunication links of each of these networks.

A further configuration of the inventive communication system isillustrated in FIG. 2F, where a second wireless network N2 a isconstituted or built by communication terminals T1 and T4 and anothersecond wireless network N2 b is built by communication terminals T2, T3,and T5. The second wireless network N2 a is connected to the othersecond wireless network N2 b over the first network N1.

A further embodiment of the invention is illustrated in FIG. 2G wherethe configuration as illustrated in FIG. 2E is extended by another firstnetwork N1 b in addition to a first network N1 a representing the firstnetwork N1 in FIG. 2E. The second network N2 built by communicationterminals T1-T5 is thus connected to the other first network N1 b overcommunication terminal T5 and communication link 27 and at the same timeconnected to the first network N1 a over communication terminal T1,communication link 21, and communication terminal T3 and communicationlink 23. The first network N1 a may be a LAN whereas the other firstnetwork Nib may be a GSM network. The second wireless network N2 may bea low rate wireless personal area network allowing each of thecommunication terminals T2 and T4 to be woken up by routed informationof the first network N1 a and the other first network N1 b.

In FIG. 3, the invention is illustrated in an embodiment of the firstnetwork N1 being an IEEE 802.3 Ethernet and the second wireless networkN2 being an—IEEE 802.15.4 LR-WPAN. As illustrated in FIG. 1, the firstnetwork N1 is connected to a server S over a connection link IB andconnected to the communication terminal T over the first connection link1A. The second wireless network N2 is connected to the communicationterminal T over the second communication link 2. The first network N1has the advantages of being a low-cost network with fast transfer ratesof approximately 100-1,000 Mb/s. The first network N1, on the otherside, shows a long startup negotiation time of approximately 1 s and apower consumption in the idle mode of approximately 10 mW. In contrastto the first network N1, the second wireless network N2 shows a slowtransfer rate of approximately 250 kb/s and the advantages of being alow-cost network, having a power consumption in the idle mode of only1-10 μW and a fast wake-up time of smaller than one ms corresponding tothe start-up negotiation time of the first network N1.

In the active mode the communication terminal T1 is connected to thefirst network N1, the terminal is fully powered using Power overEthernet, a rechargeable battery or capacitor is being charged by Powerover Ethernet, and a MCU may be able to work at full frequency allowingthe user to take advantage, of a complete set of user functionality ofthe communication terminal. Further, the communication terminal T worksas a radio/Ethernet router for other communication devices which havebeen disconnected from the first network N1 over their first interfacesand which are connected to the second wireless network N2 over theirsecond interfaces as illustrated in FIG. 2B to 2G. The communicationterminal T being connected to the second network N2 over its secondinterface I2 while being connected to the first network N1 over itsfirst interface I1 in the active mode is able to discover othercommunication devices which have been disconnected from the firstnetwork N1 and which are reachable only over the second wireless networkN2. With the communication terminal T being connected to the firstnetwork N1 over the first communication link 1A the communicationterminal T may be switched to the idle mode if the server S sends arespective request to the communication terminal T over thecommunication link IB, the first network N1 and the first communicationlink 1A to the communication terminal T.

In the idle mode, the communication terminal T is disconnected from theEthernet as the first network N1 over its first interface I1 (notshown). A rechargeable battery/capacitor is the only power source forthe communication terminal T since due to its disconnection from thefirst network N1 Power over Ethernet is not available. Caused by theidle mode the MCU of communication terminal T is in sleep mode, causingno user functionality of the communication terminal T to be available.Alternatively, a limited functionality set aver radio by using thesecond wireless network could be provided for example for emergencyoperation if the Ethernet of the first network fails or if the powersupply for fire communication terminal T cannot be maintained. In theidle mode, the communication terminal is able to send keep-alivemessages and to receive power control commands or instructions fromother devices of the second wireless network, thus communicating withother devices of the second wireless network N2 with limited datatransfer speed or rate over radio compared to the speed possible bycommunicating over the first network. A communication terminal in theactive mode discovering the communication terminal T in the idle modemay inform the server S of the communication terminal T in the idle modeby the communication terminal T sending keep-alive messages to acommunication terminal of the second wireless network acting as a routerbetween the first network and the second wireless network. With thecommunication terminal T in the idle mode being connected to the firstnetwork N1 over its second interface I2 and another communicationterminal of the second wireless network N2 acting as a router forrouting information from the first network N1 to each of thecommunication terminals of the second wireless network N2 thecommunication terminal T may be switched to the active mode if theserver S orders it by sending an activation request. Alternatively, thecommunication terminal T may switch itself from the idle mode to theactive mode if the communication terminal is required to do so. This maybe the case if the connection to the second wireless network is lost, ifa rechargeable battery or capacitor is going out of charge, or if a userinput requests the communication terminal to switch from idle mode toactive mode.

As a protocol and/or a management means for operating the first networkN1 and/or the second wireless network N2 may be considered: IPv6,6L0WPAN, multi-channel MAC, centralized routing, multi-homing, SCTP, RTPheader compression or the like. The first network N1 and/or the secondwireless network N2 may be configured as star networks, peer-to-peer orpoint-to-point networks, as illustrated in FIG. 2, or as cluster treenetworks or a combination thereof.

In FIG. 4, a flow chart of switching the communication device from theidle mode to the active mode and from the active mode and from theactive mode to the idle mode is illustrated. As a starting point 40, theidle mode 41 may be chosen. If a user input in form of pushing a buttonof the communication device or taking a handle of the communicationdevice off-hook occurs to switch to the active mode 42, thecommunication device is connected to the first network N1. If theconnection to the first network N1 over the first interface I1 fails,the communication device stays in the idle mode 41 or sends a message toother devices of the second wireless network N2. If a connection to thefirst network N1 is established, the communication device is operated inthe active mode 51. If no user input to switch to active mode isreceived by the communication device, the communication device stilltries to establish a connection to the first network N1 if a server (aspart) of the first network N1 requests the communication device toswitch to active mode 44, if the connection to the second wirelessnetwork N2 is lost, or if a rechargeable battery B or a capacitor of thecommunication device is going out of charge. If none of these casesoccurs, the communication device stays in idle mode.

If the communication device is switched to active mode 51, thecommunication device tries to connect to the second wireless network N2,53, if requested to do so by user input to switch to idle mode. If sucha connection of the communication device to the second wireless networkN2 can be established, the communication device switches to the idlemode 41. If the connection to the second wireless network N2 cannot beestablished, the communication device stays in the active mode 51 to beable to be used even if no payload data is to be transmitted. If no userinput to switch to idle mode is received by the communication device, anattempt to connect to the second wireless network still occurs if theserver requests the communication device to switch to idle mode, 54, ifthe connection to the first network N1 is lost, 55, or if therechargeable battery or capacitor is fully charged, 56. If none of thesecases occurs, the communication device may still be used by a user andtherefore stay in the active mode. Instead of a user input to switch toidle mode, the user input to switch to idle mode may be represented by amissing user input in a predetermined time window following the lastuser input.

A timer may be used for starting a time period of waiting for user inputtriggered by a previous user input.

A technical feature or several technical features which has/have beendisclosed with respect to a single or several embodiments discussedhereinbefore, e.g. the timer for starting a time period of waiting foruser input triggered by a previous user input in the embodiment of thelast paragraph, may be present also in another embodiment except itis/they are specified not to be present or it is impossible for it/themto be present for technical reasons.

With the present invention two networks for transmitting signaling andpayload data but having different properties at least with respect topower consumption in idle mode and available bandwidth are combined in asingle communication device. This combination may not require hardwarechanges but may be established in form of a software update only notsignificantly increasing the manufacturing costs of the communicationdevice. On the other side, advantages of both networks are combined inthe communication device. If the first network is an Ethernet LAN andthe second wireless network is a low rate wireless personal areanetwork, the communication device is able to work with full Ethernetspeed in the active mode and is able to reduce power consumption under 1mW in the idle mode, while maintaining the possibility to communicatewith a server of the first network and the possibility to be woken upremotely by a communication device of the first network and/or thesecond wireless network.

1-18. (canceled)
 19. A method of operating a communication devicecomprising: providing a first communication device with a firstinterface to connect to a first network that provides a first bandwidthand a first network idle power consumption at the first communicationdevice when the first communication device is connected to the firstnetwork; providing the first communication device with a secondinterface to connect to a second network that provides a secondbandwidth and a second network idle power consumption at the firstcommunication device when connected to the second network via the secondinterface, the second network idle power consumption being smaller thanthe first network idle power consumption, the second bandwidth beingsmaller than the first bandwidth; establishing a first communicationlink between the first communication device and the first network viathe first interface when the first communication device is in an activemode, the first communication link having an established physical layerand an established data link layer of the first network for payload datatransmission between the first network and the first communicationdevice; operating the first communication device to discover a secondcommunication device that has been disconnected from the first networkand is connected to the second network when the first communicationdevice is in the active mode and to function as a router when the firstcommunication device is in the active mode to route information from thefirst network over the second interface to a second communication devicethat has been disconnected from the first network and that is connectedto the second network such that the second communication device islinked to the first network via the first communication device operatingas the router; disconnecting the first communication link andestablishing a second communication link between the first communicationdevice and the second network via the second interface in response tothe first communication device being adjusted from the active mode to anidle mode; and operating the first communication device in the idle modeto exchange a keep-alive message with and to receive a power controlinstruction from a third communication device connected to the secondnetwork via the second communication link.
 20. The method of claim 19,comprising: switching the first communication device from the idle modeto the active mode in response to a request received over the secondinterface.
 21. The method of claim 19, wherein the second network is awireless network.
 22. The method of claim 19, comprising: switching thefirst communication device from the idle mode to the active mode inresponse to a request from a server of the first network received viathe second communication link.
 23. The method of claim 19, comprising:switching the first communication device from the idle mode to theactive mode in response to disconnection of the second communicationlink that connects the first communication device to the second network.24. The method of claim 19, wherein the first communication device has arechargeable battery that is charged when the first communication deviceis operated in the active mode.
 25. The method of claim 24, comprising:switching the first communication device from the active mode to theidle mode in response to the rechargeable battery being fully charged.26. The method of claim 19, comprising: switching the firstcommunication device from the idle mode to the active mode in responseto user input from a user of the first communication device.
 27. Themethod of claim 19, comprising: transmitting a message from the firstcommunication device to the third communication device via the secondcommunication link when at least one of: the first communication devicecannot be connected to the first network and the first communicationdevice cannot be charged.
 28. A communication apparatus comprising: afirst communication device comprising: a first interface configured toconnect the first communication device to a first network that providesa first bandwidth and a first network idle power consumption at thefirst communication device when the first communication device isconnected to the first network via the first interface; a secondinterface configured to connect the first communication device to asecond wireless network that provides a second bandwidth that is smallerthan the first bandwidth and a second network idle power consumptionthat is smaller than the first idle power consumption at the firstcommunication device when the first communication device is connected tothe second wireless network via the second interface; a controller unitconfigured to control the first interface and the second interface, thecontroller unit configured to control the first and second interfacessuch that the first communication device is switchable between an activemode in which the first communication device is connected to the firstnetwork via the first interface and an idle mode in which the firstcommunication device is connected to the second wireless network via thesecond interface and is not connected to the first network via the firstinterface; the controller unit configured to control the first andsecond interfaces such that: the first communication device isconfigured to establish a first communication link with the firstnetwork over the first interface when in the active mode, the firstcommunication link configured so that payload data is transmittablebetween the first communication device and first network via the firstinterface, and the first communication device is switched from theactive mode to the idle mode such that the first communication link isdisconnected and a second communication link is established between thefirst communication device and the second wireless network via thesecond interface; the first communication device configured to exchangea keep-alive message and to receive a power control instruction from asecond communication device connected to the second wireless networkwhen in the idle mode; the first communication device configured todiscover at least one third communication device that was disconnectedfrom the first network and is connected to the second wireless networkto inform the first network of the at least one third communicationdevice via the first interface when in the active mode and beingconfigured to operate as a router when in the active mode to routeinformation from the first network over the second interface to the atleast one third communication device so that the at least one thirdcommunication device is linked to the first network via the secondinterface of the first communication device.
 29. The communicationapparatus of claim 28, comprising: the first network and the secondwireless network; the first network being a local area network or aglobal area network and the second wireless network being a low ratewireless personal area network in accordance with IEEE 802.15.4.
 30. Thecommunication apparatus of claim 29, comprising: the at least one thirdcommunication device, the at least one third communication devicecomprising a plurality of second communication devices.
 31. A method ofusing a first communication device, comprising: establishing a firstcommunication link between a first communication device and a firstnetwork via a first interface of the first communication device when thefirst communication device is in an active mode, the first communicationlink configured for transmission of payload data between the firstnetwork and the first communication device; operating the firstcommunication device to discover at least one second communicationdevice that had been disconnected from the first network and isconnected to the second network while the first communication device isin the active mode and operating the first communication device while inthe active mode to function as a router when the first communicationdevice is in the active mode to route information from the first networkover a second interface of the first communication device to a secondcommunication device that has been disconnected from the first networkand that is connected to a second network such that the secondcommunication device is linked to the first network via the firstcommunication device operating as the router; switching the firstcommunication device from the active mode to an idle mode such that thefirst communication link is disconnected so that the first communicationdevice is no longer connected to the first network over the firstinterface and a second communication link is established between thefirst communication device and the second network via a second interfaceof the first communication device, the second network being a wirelessnetwork; and operating the first communication device in the idle modeto exchange a keep-alive message with and to receive a power controlinstruction from one of: the second communication device and a thirdcommunication device connected to the second network via the secondcommunication link.
 32. The method of claim 31, wherein the firstcommunication device has a first idle power consumption and a firstbandwidth when operated in the active mode and connected to the firstnetwork via the first interface and the first communication device has asecond bandwidth that is smaller than the first bandwidth and a secondidle power consumption that is smaller than the first idle powerconsumption when operated in the idle mode and connected to the secondnetwork via the second interface.
 33. The method of claim 32, whereinthe first communication device is only configured to transmit signalingto the first network via the second interface when in the idle mode andis unable to transmit payload data when in the idle mode.
 34. The methodof claim 33, wherein the first communication device is configured totransmit payload data and signaling via the first network when in theactive mode.
 35. The method of claim 34, wherein the first network is alocal area network and the second network is a wireless personal areanetwork.
 36. The method of claim 32, comprising: switching the firstcommunication device from the idle mode to the active mode in responseto a request from a server of the first network received via the secondinterface.
 37. The method of claim 31, comprising: transmitting amessage from the first communication device to the third communicationdevice via the second communication link when the first communicationdevice is in the idle mode and cannot be connected to the first network.38. The method of claim 31, wherein the first communication device has arechargeable battery, the method comprising: transmitting a message fromthe first communication device to the third communication device via thesecond communication link when the first communication device is in theidle mode and the rechargeable battery cannot be charged.